This invention relates to the treatment of liquids, and more particularly to water filters that are precoated by replaceable powders.
Liquid filters that provide the high purity water required for the steam generation of electricity are commonly precoated on the outside with diatomaceous earth or powdered ion exchange resins. Such filters may have five hundred or more individual filter elements that are each over six feet in length. Full utilization of the water treating capability of such precoat materials requires that the precoat be uniformly applied over the full length of each filter element. When the energy used to produce the steam for electric power generation comes from a nuclear reactor, the filtering equipment becomes highly radioactive, and the individual filter elements must be capable of being installed and removed from a remote location. During prolonged usage, the dimensions of the individual filter element may vary, as for example when a wound nylon filter element shrinks during high temperature service.